I picked up a few C1100s the other day and everything is working great except for none of the machines will recognize any PCIe card. I've gone through the BIOS and toggled everything related to PCIe and i've tried multiple types of cards in the riser. I've even tried without the riser entirely.
Bottom line - Nothing inserted in the PCIe slot is recognized.
If you recognized the PCI slot card they are gone through with Bios System and it will multi type of can be use for BIOS